Transcription of a “silent” cyanobacterial psbA gene is induced by microaerobic conditions
Cyanobacteria, contrary to higher plants, have a small psbA gene family encoding the reaction centre D1 protein subunit of photosystem II, the first macromolecular pigment-protein complex of the photosynthetic electron transport chain. Modulation of expression of multiple psbA genes in the family al...
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Published in | Biochimica et biophysica acta Vol. 1787; no. 2; pp. 105 - 112 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Netherlands
Elsevier B.V
01.02.2009
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Subjects | |
Online Access | Get full text |
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Summary: | Cyanobacteria, contrary to higher plants, have a small
psbA gene family encoding the reaction centre D1 protein subunit of photosystem II, the first macromolecular pigment-protein complex of the photosynthetic electron transport chain. Modulation of expression of multiple
psbA genes in the family allows cyanobacteria to adapt to changing environmental conditions. To date, two different strategies for regulation of the
psbA genes have emerged. One, characterized in
Synechocystis PCC6803 and
Gloeobacter violaceus PCC7421 involves the increased expression of one type of D1 protein to cope with the increased rate of damage. The other strategy, in
Synechococcus PCC7942 and
Anabaena PCC7120, is to replace the existing D1 with a new D1 form for the duration of the stress. However, most of the
psbA gene families characterized to date contain also a divergent, apparently silent
psbA gene of unknown function. This gene, present in
Synechocystis,
Anabaena and
Thermosynechococcus elongatus BP-1 was not induced by any stress condition applied so far. Our data shows a reversible induction of the divergent
psbA gene during the onset of argon-induced microaerobic conditions in
Synechocystis,
Anabaena and
Thermosynechococcus elongatus. The unitary functional response of three unrelated cyanobacterial species, namely the induction of the expression of the divergent
psbA gene as a reaction to the same environmental cue, indicates that these genes and the protein they encode are part of a specific cellular response to microaerobic conditions. There are no specific primary structure similarities between the different microaerobic inducible D1 forms, designated as D1′. Only three amino acid residues are consistently conserved in D1′. These modifications are: G80 to A, F158 to L and T286 to L.
In silico mutation of the published D1 structure from
Thermosynechococcus did not reveal major modifications. The point by point effects of the mutations on the local environment of the PSII structure are also discussed. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0005-2728 0006-3002 1879-2650 1879-2650 1878-2434 |
DOI: | 10.1016/j.bbabio.2008.12.002 |